Origin and control of random macroscopic defects induced variability in low-temperature photoconductivity of layered n-InSe
摘要
To elucidate the origins of the dispersion in photoelectric parameters and characteristics observed among different indium monoselenide (n-InSe) crystal samples, a comprehensive experimental study was conducted. The investigation examined the dependence of the principal characteristics of intrinsic photoconductivity on several factors: the initial dark specific resistance measured at 77 K (ρ77 = 103–107 Ω·cm); the chemical nature and concentration of introduced rare-earth element (REE) impurities (Gd, Ho, and Dy; NREE = 10−5–10−1 at.%); temperature (T = 77–350 K); the magnitude of an externally applied galvanic electric field (ranging from extremely weak fields up to E = 3 × 103 V/cm); and both the intensity (up to 5 × 102) and wavelength (0.40–1.50 μm) of incident light. It has been established that the scatter of photoconductivity characteristics from sample to sample in pure n-InSe crystals, detected in the low-temperature region (at T ≤ 250 K), is due to the occurrence of random macroscopic defects (RMD) in these samples during their manufacture due to the weakness of the interlayer bond. By changing the content of introduced rare-earth impurities (NREE), the magnitude of the injecting electric field applied to the studied sample, and the temperature, it is possible to control the influence of these RMD on the photoconductivity characteristics, and at NREE ≈ 10−1 at.%, reduce it to zero.